<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <h1>一级标签</h1>
    <h2>二级标签</h2>
    <h3>三级标签</h3>
    <h4>四级标签</h4>
    <h5>五级标签</h5>
    <h6>六级标签</h6>
</body>

</html>